抄録
This report describes a new shell freezing method for vials devised in our study. For aseptic pharmaceutical products, the freeze drying process should be as brief as possible not only from economical view point but also from aseptic criteria. It is well known that by use of shell freezing technique the process time must be shortened drastically. However, the conventional techniques are not suitable for large scale production because of complicated handling in which vials need to be fixed to the rotational axes one after another. In our new method, product in vials is shell frozen on the inner surface of the vials which are rolled on the cooled surface by use of the chain conveyer system. The good thermal contact between the vials and the cooled surface is obtained by a thin ethanol film laid on the cooled surface. Freezing of an aqueous solution of 20wt% lactose in volume of 1.75ml put in a vial of 18mm inner diameter has been completed within 1 minute with on effective length of one to two meter rolling. The drying time is shortened to approximately 5 hours from 20 hours required in the conventional methods. Five hour cycle will be good enough to perform continuous freeze drying of vials.
